Extend AppSignature trait with Signature

[Klapeyron]

sp_application_crypto::AppPublic requires sp_core::crypto::Public:

/// Application-specific public key.
pub trait AppPublic: AppCrypto + Public + Debug + MaybeHash + Codec {
	/// The wrapped type which is just a plain instance of `Public`.
	type Generic: IsWrappedBy<Self> + Public + Debug + MaybeHash + Codec;
}

but it looks like similar requirement is missing for sp_application_crypto::AppSignature and sp_core::crypto::Signature:

/// Application-specific signature.
pub trait AppSignature: AppCrypto + Eq + PartialEq + Debug + Clone {
	/// The wrapped type which is just a plain instance of `Signature`.
	type Generic: IsWrappedBy<Self> + Eq + PartialEq + Debug;
}

This PR extends sp_application_crypto::AppSignature trait with sp_core::crypto::Signature.

[bkchr]

/cmd prdoc --bump major

[github-actions]

Command "prdoc --bump major" has failed ❌! See logs here

[bkchr]

/cmd prdoc --bump major --audience runtime_dev

[github-actions]

Command "prdoc --bump major --audience runtime_dev" has failed ❌! See logs here

[github-actions]

Review required! Latest push from author must always be reviewed

[michalkucharczyk]

@Klapeyron, in future, you can merge the origin/master into your branch and push it, instead of force pushing (which is not preferred). Thanks.

[Klapeyron]

yea, I wanted to reduce number of commits, but it is making more issues xd

[Klapeyron]

Let me know if there’s anything I can do to help move this PR forward

[skunert]

@Klapeyron I think you need to do nothing. When you merge master, the approvals get reset because we need to review the newest commit (because you are first-time contributor). Please hold off, we will approve and merge.